1. Field of the Invention
This invention relates specifically to multiple pane window units, and more specifically to multiple pane window units installed in a fashion known as "butt-glazed."
2. Description of the Prior Art
Prior art window units of this type are installed from the outside of the building and require the use of a temporary fastening method which has to remain in place until the adhesive material around the window unit has set properly which temporary fastening method is then removed, and which units also require a permanent upright stiffener on the inside of the building which stiffener is not desirable because it tends to obscure the view from the inside of the building and to prohibit placing furniture or drapes close to the windows.
Conventional multiple pane window units which are glazed in a conventional fashion are supported against wind load forces by clamping them into a window frame. Such windows are provided with relatively weak spacers between the panes of glass.
However, in butt glazing the vertical edges of the window unit are not supported in a window frame, and support is given to the vertical edges of the window unit by an interior stiffener. To install the conventional butt-glazed window unit, it is clamped in place by a temporary fastening method while the inside structrual silicone adhesive, which is applied to the inner face of the units adjacent to the vertical edges, is curing. After curing, the structural silicone adhesive bonds the vertical stiffener to the window units, thus achieving the necessary structural strength.
Moreover, if a butt-glazed window unit should break and have to be replaced, the replacement window unit must also be installed from the outside of the building in the same manner, and this presents problems and is expensive.
Another problem in the art is how to arrange a series of butt-glazed window units to form the cords of a curve to conform to the curved contours of a modern building.
Conventionally, the series of window units are set in the appropriate positions so as to form the cords of a curve, but the joints between abutting window units are large and vary in size, and such joints give an uneven appearance that is undesirable. Also, such joints are difficult to seal, they obscure vision, and in cases where the outboard pane is wider than the inboard pane, the vertical edges of the outboard pane are exposed to damage in handling and in installing.